Alkali metal dispersions



Patented Apr. 14, 1953 UNITED STATES PATENT OFFICE ALKALI METAL DISPERSIONS No Drawing. Application June 23, 1950-, Serial No. 170,038

7 15 Claims. 1

This invention relates to alkali metal dispersions in inert liquids and particularly to fluid dispersions and their preparation.

Dispersions of alkali metals in inert organic liquids have been prepared by suitably agitating a mixture of the metal and an inert liquid at a temperature above the melting point of the metal. Such products contain relatively coarsely dispersed metal particles which tend to settle rapidly and to reagglomerate. The preparation of dispersions in which particle settling and reagglomeration are reduced or eliminated is described by Hansley, Patent 2,394,608, the method involving effecting the dispersion in the presence of an alkali metal soap. The particle size of the dispersed metal obtained by that method averages about 50 to 200 microns and generally about 100 microns. Dispersions containing metal particles of much smaller size are desirable and valuable for many purposes and the present invention is concerned with such products and their preparation.

One object of the invention is to provide new and improved fluid dispersions of finely divided alkali metals in inert organic liquids, particularly hydrocarbon liquids, and a practical method for making such dispersions. Another object is to provide stable, fluid dispersions of such metals in which the average particle size of the dispersed metal does not exceed about 50 microns and preferably is less than 25 microns, A further object is to provide diesel fuels having improved ignition characteristics due to the presence therein of small amounts of alkali metal finely dispersed in the hydrocarbon fuel. These and other objects will be apparent from the following description of the invention.

The above objects are accomplished in accordance with the invention in general by preparing an emulsion of finely divided molten particles of an alkali metal in an inert organic liquid having a boiling point above the melting point of the metal in the presence of an emulsifying agent of the type and in the proportions hereinafter indicated. The dispersions may be prepared by heating together the metal and the inert liquid to a temperature between the melting point of the metal and the boiling point of the liquid in the presence of the emulsifying agent, while effectively agitating the mixture and then cooling the resulting emulsion. The emulsifying agent may be present during the entire operation or may be added during the latter part of the period of agitation. Agitation may be accomplished by any desired method which will effect the proper degree of subdivision of the metal.

Fluid dispersions prepared as above indicated contain the metal in a stable finely divided active form useful for many purposes. Thus, they are useful as the source of alkali metal in carrying out chemical reactions, e. g., metallation and reduction reactions, and in petroleum refining processes. For some purposes dispersions containing low concentrations are desirable and such dispersions may generally be prepared by diluting a more concentrated product with any suitable inert organic liquid. such as a petroleum hydrocarbon. The unusually finely divided form of the metal in the present products makes them useful as additives for diesel fuels of inferior ignition characteristics, the effect of the finely divided metal in such fuels being to increase the cetane number of the fuel.

A convenient form of apparatus for use in preparing the present dispersions is described and illustrated diagrammatically in Hansley Patents 2,487,333 and 2,487,334. The apparatus comprises an emulsifying vessel and a circulating system, both immersed in an oil bath heated to a temperature at which the alkali metal is molten. The circulating system includes a pump having conduits leading to and from the emulsifying vessel and positioned below the liquid level in the vessel, preferably near the bottom. The alkali metal and inert liquid are placed in the vessel and heated by the oil bath to a temperature above the melting point of the metal. Operation of the pump circulates the resulting mixture from the vessel through the pump and back to the vessel. The end of the conduit returning material to the vessel is extended a short distance into the vessel and is provided with a nozzle having an orifice of suitable size, e. g., to in. in diameter. Pumping the mixture at high velocity through the orifice effectively subdivides the metal. Preferably, the stream from the orifice is directed at an abrupt angle, e. g. against a splash plate positioned a short distance, e. g. in., from the orifice. The presence in the system of an emulsifying agent, e. g., an alkali metal derivative of an unsaturated hydrocarbon of the type herein defined, facilitates subdivision of the metal and stabilizes the resulting emulsion and also the dispersion resulting when the emulsion is cooled.-

The term alkali metals is used herein to include lithium, sodium, potassium, rubidium, cesium and alloys of two or more such metals with each other, for example, potassium-sodium alloys.

The terms emulsion and emulsifying agent are used herein with reference to the systems when they are at temperatures above the melting point of the metal, i. e., under conditions where the metal is liquid. The terms dispersion and dispersing agent are employed with reference to the same systems when they are at a temperature below the melting point of the metal.

The present dispersions are prepared by effectively agitating the alkali metal in the inert organic dispersing liquid in the presence of an alkali metal derivative of an unsaturated hydrocarbon having a molecular weight of'about 100 to 2,000 and an iodine number of at least 50, e. g., 50 to 450. Derivatives of hydrocarbons of molecular weight of about 200 to 1,500 are preferred. We have found that such derivatives are highly effective emulsifying agents and may be used to prepare fluid dispersions having very finely divided metal particles. Dispersions in which the diameter of the metal particles is less than 100 microns and averaging not more than 50 and generally less than 25 are obtained. Products in -which the'particle size of the dispersed metal ranges from 1 to microns can be readily obtained. The present dispersing agents. can, of course, be used to prepare products in which the metal is more coarsely dispersed depending upon the effectiveness of the agitation and the amount of dispersing agent used; however, it is generally desired to obtain as high a degree of sub- I division as possible and stable dispersions which the diameter of the metal particles ranges from about 1 to microns and averages less than 10 microns may be readily prepared in accordance with the present invention.

Ebert et al. Patent 2,209,746 discloses alkali -metal dispersions of relatively low metal content in which the metal is dispersed in substances, such as soft parafiin wax, butadiene to the alkali metal. Polybutadiene having a proper viscosity of 32 to 40 is mentioned.

Such viscosities correspond to molecular weights of around 20,000. The products of the patent metal derivatives of the unsaturated hydrocarbons, rather than by the solid or semi-solid condition of the medium in which the metal is dispersed as is the case with the products of the patent.

The amount of the dispersing agent and the ratio thereof to the amount of metal being dispersed are important factors in preparing stable compositions which are fluid at ordinary temperatures, e. g. -30" 0., especially when such compositions contain high concentrations of metal, i. e., at least 20%, in-flnely divided form. In general the dispersing agent,,calculated as the parent unsaturated hydrocarbon, should not exceed more than 15% e. g., should be equal to about 0.5 to 10% of the total weight of the composition. Also, the amount of dispersing agent, calculated as the parent hydrocarbon, should equal from about 1 to preferably 2 to 15%, of the weight of the metal being dispersed. Smaller proportions are generally not effective to produce the desired stable flne dispersions while larger proportions, e. g., over 25%, are unnecessary and generally undesirable because they unduly contaminate the product with material serving no useful purpose. Furthermore, many of these unsaturatedghydrocarbons react vigorously with alkali metals so that when preparing the metal derivative in situ, as is preferred, the use of much larger amounts of the parent hydrocarbon frequently results in reactions which are uncontrollable and hazardous.

The effectiveness of the present alkali metal derivatives as emulsifying agents depends chiefly on the proportion of alkali metal to carbon atoms in the aliphatic portion of the molecule, which inturn depends upon the degree of unsaturation in the parent hydrocarbon. Hydrocarbons having iodine numbers of 75 to 450 and preferably 100 to 350, yield derivatives which are polymers and polyisobutylene, which are inert 40 are pastes in which the metal is maintained vin the subdivided state by the pasty nature especially effective, particularly when the molecular weight of the parent hydrocarbon is within the range of about 200 to 1,500.

Especially effective are the derivatives of hydrocarbons in which the ratio of the number of ethylenic linkages, i. e. C=C linkages; present in all aliphatic and/or cycloaliphatic residues, to the number of aliphatic carbon atoms in the total molecule is 1 to 5:20. A branched chain aliphatic structure is especially desirable.

The unsaturation mentioned with respect to hydrocarbons from which the alkali metal derivatives are derived has specific reference to unsaturation occurring in the aliphatic or cycloaliphatic portion of the hydrocarbon molecule. The degree of unsaturation is expressed in terms of the iodine number (Wijs) of the hydrocarbon. Y

The active alkali metal derivative will generally be formed in situ by adding the parent unsaturated hydrocarbon to the emulsion system or by adding the metal to a mixture of the inert liquid and the unsaturated hydrocarbon. The hydrocarbon should be soluble in the inert liquid, in an amount corresponding to at least 0.1% by weight of the mixture. The exact amount to be added in any instance will depend upon the specific unsaturated hydrocarbon used, its solubility, the degree of dispersion desired and the amount of metal to be dispersed. The amount also will depend to some extent upon the inert liquid in which the metal is to be dispersed. Generally, the more metal to be dispersed, the more dispersing agent will be required. Any solid hydrocarbon utilized should be added in the form of a solution, e. g. dissolved in an inert hydrocarbon solvent such as kerosene, white oil,

fuel oil, toluene, xylene or the like.

Typical of the unsaturated hydrocarbons whose alkali metal derivatives are effective for the present purpose are the polymers of conjugated diolefines such "as 1,3-butadiene and its homologues, e. g., 2-methyl-1,3-butadiene, 2,3- dimethyl-1,3-butadiene and 1,3-pentadiene; and the cyclic conjugated diolefines such as cyclopentadiene and dicyclopentadiene. The alkali metal derivatives of copolymers of two or more of such hydrocarbons are also usable.

Other useful emulsifying agents are the alkali metal derivatives of copolymers of conjugated diolefine hydrocarbons of the above type with polymerizable monoolefine hydrocarbons containing the CH2=C group, which copolymers are formed by polymerizing a mixture of the monomers in which the ratio of the diolefine to monoolefine is such that the'resulting polymer will have an iodine number of at least 50. Specific examples are copolymers of butadiene with styrene, isobutylene, or ethylene.

The alkali metal derivatives of the above types of polymers and copolymers may be prepared by adding the preformed polymer or copolymer dissolved in a suitable solvent to the emulsification system under agitation. When practicing the invention in this manner, polymer or copolymer prepared by any of the well-known methods for obtaining such products may be employed, provided they meet the requirements with respect to iodine number and molecular weight. A preferred way is to add the monomeric polymerizable hydrocarbon or, a mixture of such hydrocarbons, in suitable amounts to the emulsification system which is agitated and maintained at a temperature above the melting point of the metal, whereby the hydrocarbon is polymerized and the polymer reacts with a small part of the metal to form the active alkali derivative in situ.

Also, highly eifective as emulsifying agents for practicing the present invention are the alkali metal derivatives of the addition compounds of polymerizable conjugated diolefine hydrocarbons of the type mentioned above with non-polymerizable alkyl substituted aromatic hydrocarbons having at least one hydrogen atom on the alpha carbon, i. e., the carbon atom directly attached to the aromatic residue, of at least one alkyl substituent group. Of the hydrocarbons of the latter type, those having from 1 to 2 alkyl groups of l to 2 carbons each, with at least one of said groups having at least 2 hydrogens on the alpha carbon are preferred. Specific examples of these substituted aromatic hydrocarbons are: toluene, the xylenes, 1,3,5-trimethyl benzene, n-propyl benzene, para-cymene, ethyl benzene, alpha-methyl naphthalene and beta-ethyl naphthalene.

These addition compounds of diolefine hydrocarbons with alkyl substituted aromatic hydrocarbons may be prepared by reacting the hydrocarbons together under conditions which favor polymerization of the diolefine hydrocarbon, e. g., in the presence of a polymerization catalyst for the diolefine at elevated temperature. Finely divided alkali metals are suitable catalysts for this purpose. A mixture of unsaturated addition products of varying chain length is formed (see Arbusov et al., Comptes Rendus (Doklady) de l'Academie des Sciences de lUSSR (1943), vol. 39, No. 8, p. 311). These addition products have the general formula Y(A)nZ, wherein A is a divalent aliphatic chain derived from one or more diolefine molecules; n is an integer representing the number of diolefine molecules which have united to form A; and Y and Z are fragments terminally attached to chain A, which fragments together constituted one molecule of the starting substituted aromatic hydrocarbon. Z in the above formula, of course, represents a hydrogen atom which originally was present on an alpha carbon of an alkyl substituent group of the substituted aromatic hydrocarbon, while Y represents the remaining part of the substituted aromatic hydrocarbon. Chain A is unsaturated and contains one double bond linkage for each diolefine molecule added. These addition compounds react readily with alkali metals under the conditions employed in preparing the present emulsions to form alkali metal derivatives of the hydrocarbon addition compounds which are active emulsifying agents for the present purpose. As indicated, such derivatives will generally be formed in situ by addition to the emulsifying system of the unsaturated hydrocarbon addition compound, or a mixture of such compounds, in suitable amounts. However, the preformed metal derivatives may be added if desired.

The invention is further illustrated by the following examples in which the apparatus described and illustrated in Hansley Patents 2,487,333 and 2,487,334 was used.

Example 1 A charge of 450 g. each of sodium and paracymene was heated in the emulsifying vessel of the apparatus to 105 to 107 C. While pumping the charge, 60 g. of a butadiene-xylene addition product was added gradually. Cooling the resulting emulsion to room temperature gave a stable dispersion in which the sodium particles ranged from 1 to 15 microns in diameter. The dispersion was fluid and poured readily.

The butadiene-xylene addition product used above was prepared by passing butadiene gas into a mixture, maintained at to 98 C., of 900 g. of xylene and 8.2 g. of sodium added as a finely divided 45 dispersion of sodium in toluene. 465 g. of butadiene was added. The resulting mixture was steamed to destroy free sodium and hydrolyze sodium compounds, neutralized with hydrochloric acid and then washed with water. After centrifuging to remove water, materials boiling below 220 C. at 0.5 mm. were stripped from the reaction mixture by distillation under reduced pressure. The mixture of butadiene-xylene addition products remaining as the still residue was employed in Example 1. These products had molecular weights ranging from 935 to 999, the average being 972. The lower molecular weight addition products corresponding to molecular weights of 182 to 201 were also effective for the present purpose.

Example 2 450 g. of sodium in an equal weight of white kerosene was melted and emulsified in the apparatus described during a period of 115 min., during which time 90 g. of isoprene was added in increments of 4.5 to 22.5 g. The diameter of the dispersed sodium particles ranged from 1 to 15 microns and averaged 6 to 9. Upon cooling to room temperature a stable fluid dispersion of a thin consistency was obtained.

Example 3 300 g. of sodium was emulsified in 600 g. of white oil as in the previous example while 27 g. of methyl pentadiene was added in 9 g. increments alternated with two 4.5 g. additions of oleic acid. The time during the additions was 85 min. after which pumping was continued for an additional 20 min. A stable fluid dispersion was obtained in which the sodium particles were less than 6 microns in diameter, the average being 2 to 3.

Example 4 300 g. of sodium was melted at -6 C. in 600 g. of white oil in the emulsifier. Pumping produced a coarse emulsion. 24 g. of dicyclopentadiene were added in three increments, then 6 g. of oleic acid, then 6 g. more of dicyclopentadiene followed by 3 g. more of oleic acid. Pumping was continuous during these additions and for 15 minutes afterwards. Cooling gave a stable, fluid dispersion containing sodium particles of diameter ranging from 1 to 12 microns.

Example 5 300 g. of sodimn was melted in 600 g. of white oil and the pump was started. Two 13.5 g. 1

tions of isoprene were added 25 minutes apart followed by 9 g. oleic acid then 9 g. more of isoprene and, finally, 4.5 g. more of the acid. Pumpin was continued until after a total of 130 minutes the sodium had been broken down into particles of diameter ranging from 0.5 to 12 microns and averaging 3. The resulting dispersion was fluid and stable.

Example 6 A coarse emulsion of 300 g. of sodium in 600 g. of white oil was prepared at about 105 C. employing the apparatus and general technique previously described. While continuing pumping of the mixture through the orifice, 45.6 g. of butadiene gas Was added during 24 minutes, Upon cooling the resulting emulsion a stable, fluid dispersion was obtained in which the diameter of the sodium particles ranged from 1 to 15 microns and averaged about 6.

Example 7 An emulsion of 400 g. sodium in an equal wei of white oil was prepared at a temperature of Example 8 An emulsion of 400 g. of sodium in 400 g. of toluene was prepared employing the equipment and general technique described above. During emulsification 28 g. of a butadiene-styrene copolymer was added to the system over a period of 1 hour and subsequently 8 g. of oleic acid also was vadded. The final particle size of the metal particles in the fluid dispersion ranged from 145 microns and averaged 6-9.

The copolymer employed in the above example was prepared by polymerizing a mixture of styrene and butadiene in a benzene solution at 60-70" C. in the presence of finely divided sodium as catalyst, the weight ratio of butadienezstyrene employed being 75:25. Its molecular weight was in the range 1277 to 1332 and averaged about 1305.

The molecular weights of polymers prepared in situ in the emulsifying system as illustrated in Examples 2 to 6 are low and fall chiefly in the range 200 to 1,500.

The above examples illustrate the preparation of sodium dispersions. Dispersions of other alkali metals and alloys of two or more alkali metals may be prepared by similar procedures.

The accepted index for the ignition quality of diesel fuels is the cetane number. The higher such number, the more readily the fuel ignite on compression. With the increasing use of diesel engines for the generation of power, there is a great demand for hydrocarbon fuels with ignition characteristics that will permit their use in a compression-ignition, i. e., diesel, cycle Without excessive time lag in ignition. Modern highspeed engines will not operate smoothly with a slow-igniting fuel. Excessive ignition lag leads to incomplete and inefficient combustion, rough running, and heavy smoke formation. There is a recognized need for effective and economical ignition accelerators that will permit the use as diesel fuels of petroleum distillates not now satisfactory for this use because of their inferior lenition quality.

Alkali metals are effective ignition accelerators for diesel fuels, particularly when the metal is present in finely divided form. But small amounts, e. g., on the order of 0.1%, of the metal are required to produce a relatively large increase in the cetane number when added to diesel fuels of inferior ignition characteristics. It has been discovered that alkali metal dispersions prepared as illustrated by the above examples and containing the present dispersing agents are useful as diesel fuel additives because of the stability of the dispersions and the extremely finely divided condition of the dispersed metal. Some improvement in cetane number is generally realized with additions of such dispersions in amounts corresponding to a metal concentration in the fuel of as low as about 0.001 Metal concentrations exceeding about 0.5% are not recommended since greater amounts generally do not further improve the cetane number. Concentrations within the range 0.01 to 0.2% are preferred.

The effectiveness of the present dispersions as diesel fuel additives is illustrated in the following example.

Example 9 A stable, fluid composition was prepared as illustrated generally above. It contained 36.0% dispersed sodium particles of diameter less than 25 microns and averaging less than 15 microns; 59.3% petroleum hydrocarbon dispersing liquid, chiefly White oil; 3.3% polymethylpentadiene, formed in situ as illustrated in Example 3; and 1.4 of a butadiene-styren type synthetic rubber (GRS17) which served as a thickening agent.

To a synthetic diesel fuel consisting of a mixture of equal volumes of #10 white oil and isooctane, sufiicient of the above dispersion was added to give a sodium content of 0.1% in the fuel. This amount of the dispersion raised the cetane number of the synthetic fuel from 48 to 66.

When employing the present dispersions as additives to diesel fuels as illustrated above, the

ratio of dispersing agent to dispersed alkali metal in the fuel will, of course, be the same as in the dispersion added. The particle size of the dispersed metal in the fuel should be less than microns and should average not more than 50. Preferably the average particle size will be less than 25 microns.

In the preparation of the present dispersions the emulsifying agent or the hydrocarbon from which it is formed may be added initially to the ,mixture of metal and inert liquid. The preferred method involves effecting a preliminary emulsification solely by means of agitation. The emulsifying agent, or preferably the hydrocarbon from which it may be formed in situ, is then added and agitation is continued for a short time thereafter until the desired or maximum degree of subdivision is attained. The resulting emulsion may then be cooled to ordinary temperatures, without requiring special precaution in handling during eral stability of the dispersion are retained during 9 cooling and upon dilution of the resulting dispersion with inert liquids.

Addition of the emulsifying agent or hydrocarbon from which it is derived to a mixture of molten alkali metal and inert liquid under agitation, particularly when the mixture contains around 30 to 65% of alkali metal by weight, may result in some instances in final dispersions which tend to be somewhat viscous. By the addition thereto of a small amount of a higher fatty acid, or an alkali metal soap thereof, the fluidity of the prod not is greatly improved. When an acid is added it reacts immediately with the metal to form a soap. Such use of a soap formed in situ by the addition of a higher fatty acid is preferred. Any of the known higher fatty acids, either saturated or unsaturated and having either a straight or a branched chain structure, may be used. Specific examples of such acids are: hexoic, diethyl acetic, heptoic, octoic, nonoic, capric, undecylic, lauric, myristic, palmitic, margaric, stearic, arachidic, cerotic, melissic, oleic and erucic acids. Generally, only small amounts of the acids are required and amounts within the range 0.005 to 0.1% based on the total weight of the dispersion give excellent thinning results. The physical efiect here is believed to be that of protective colloid action. Larger amounts, e. g., 0.1 to form thioxotropic gels as shown in Hansley Patent 2,394,608.

The extent of subdivision of the metal in the inert liquid will depend upon the effectiveness of the agitation provided during emulsification, the amount of metal being dispersed, the identity of the emulsifying agent used and the concentration of the agent in the system. It has been found, however, that amounts of the present agents, calculated as their parent hydrocarbons, in excess of about 25% on the weight of the metal being dispersed are unnecessary and serve no useful purpose in the systems. For amounts below about 25%, the extent of subdivision realized generally increases as the concentration of the agent is increased.

The present dispersion may be prepared so as to contain any desired amount of dispersed metal which is practical in their preparation and use. For many uses, metal concentrations of 20 to 65% by weight will be most practical and preferred. Concentrations above about 65% yield dispersions which are not generally sufficiently fiuid for handling purposes. Dispersions containing less than about 20% metal may be valuable and desirable for certain purposes. Dispersions containing such low concentrations may be prepared as illustrated in Examples 1 to 8 but are generally most practically made by diluting more concentrated products with and inert liquid such as benzene, toluene, xylene, white oils, minerol oils, refined diesel fuels and the like. Diluents boiling either above or below the melting point of the metal may be used.

Any temperature between the melting point of the alkali metal and the boiling or decomposition point of the inert organic dispersing liquid may be employed in preparing the present products. The preferred temperature is generally within the range of from just above to about 10 to C. above the melting point of the metal. In the case of sodium the preferred range is about 100 to 115 C.

Any organic liquid may be used in preparing the present dispersions so long as it is inert to the alkali metal and has a boiling point above the melting point of the metal under the conditions of use. Examples of such liquids are: xylene, toluene, various petroleum solvents such as kerosene, straight-run gas oil, white oil and the like; and inert ethers such as di-n-butyl ether and methyl oleyl ether. Inert liquids which boil below the melting point of the metal at atmospheric pressure may be used successfully under pressures which raise their boiling point to above the melting point of the metal.

We claim:

1. A fluid composition comprising a dispersion of an alkali metal in an organic liquid inert to said metal and having a boiling point above the melting point of said metal, in which composition the size of the dispersed metal particles averages not more than 50 microns in diameter, said composition containing an alkali metal derivative of an unsaturated hydrocarbon having a molecular weight of about to 2,000 and an iodine number of 50 to 450 in an amount not exceeding 15% by weight of said composition and equal to l to 25% by weight of the alkali metal content of said composition, said amount of said derivative being calculated in terms of its parent unsaturated hydrocarbon.

2. A composition according to claim 1 wherein the inert liquid is a hydrocarbon and the alkali metal derivative is a derivative of a hydrocarbon having a molecular weight of about 200 to 1,500 and an iodine number of 100 to 350.

3. A composition according to claim 1 containing 20 to 65% of alkali metal and in which the alkali metal derivative, calculated as its parent unsaturated hydrocarbon, represents 2 to 15% of the weight of the dispersed metal.

4. A composition according to claim 1 containing 0.005 to 5% by weight of an alkali metal soap of a higher fatty acid.

5. A composition according to claim 1 wherein the alkali metal derivative is a derivativ of a polymer of a conjugated polymerizable diolefine hydrocarbon.

6. A composition according to claim 1 wherein the alkali metal derivative is a derivative of a copolymer of a polymerizable conjugated diolefine hydrocarbon with a polymerizable monoolefine hydrocarbon.

7. A composition according to claim 1 wherein the alkali metal derivative is a derivative of an addition product of a polymerizable conjugated diolefine hydrocarbon with a non-polymerizable alkyl substituted aromatic hydrocarbon having at least one hydrogen atom on an alpha carbon atom of at least one alkyl substituent group.

8. A composition according to claim 1 wherein the dispersed metal is sodium and the alkali metal derivative is a sodium derivative.

9. A method for the production of a dispersion of an alkali metal in an organic liquid inert to said metal and having a boiling point above the melting point of said metal, in which dispersion the size of the dispersed metal particles will average not more than 50 microns in diameter, comprising agitating a mixture of said metal and said liquid at a temperature between the melting point of said metal and the boiling point of said liquid in the presence of an alkali metal derivative of an unsaturated hydrocarbon having a molecular weight of about 100 to 2,000 and an iodine number of 50 to 450, said derivative being present in an amount not exceeding 15% by weight of the total mixture and equal to 1 to 25% by weight of the alkali metal content thereof, said amount of said derivative being calculated in terms of its parent unsaturated hydrocarbon.

10. A method according to claim 9 wherein th inert liquid is a hydrocarbon and the alkali metal derivative of the unsaturated hydrocarbon is formed in situ.

11. A method according to claim 10 wherein the alkali metal content of the mixture is 20 to 65% and the content of the alkali metal derivative, calculated as its parent hydrocarbon, is 2 to 15% of said alkali metal content.

12. A method according to claim 10 wherein 0.005 to 5% by weight of a higher fatty acid is added to the mixture.

13. A fuel composition for compression-ignition engines of the diesel type consisting essentially of a diesel fuel, 0.001 to 0.5% of an alkali metal present as dispersed metal particles of diameter averaging not more than 50 microns, and an alkali metal derivative of an unsaturated hydrocarbon having a molecular weight of about 100 to 2,000 and an iodine number of 50 to 450, said derivative being present in an amount, calculated as its parent of the weight of said dispersed metal.

14. A fuel according to claim 13 wherein the 1 concentration of dispersed alkali metal is 0.01 to 0.2% and the average diameter of the dispersed particles is less than 25 microns. 15. A fuel according to claim 13 wherein the alkali metal is sodium and the alkali metal derivative is a sodium derivative.

VIRGIL L. HANSLEY. WILLARD JOHN P. HILTS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,209,746 Ebert et al. July 30, 1940 2,394,608 Hansley Feb. 12, 1946 2,487,333 Hansley Nov. 8, 1949 2,487,334 Hansley Nov. 8, 1949 2,506,857 Crouch May 9, 1950 hydrocarbon, equal to 1 to 

1. A FLUID COMPOSITION COMPRISING A DISPERSION OF AN ALKALI METAL IN AN ORGANIC LIQUID INERT TO SAID METAL AND HAVING A BOILING POINT ABOVE THE MELTING POINT OF SAID METAL, IN WHICH COMPOSITION THE SIZE OF THE DISPERSED METAL PARTICLES AVERAGES NOT MORE THAN 50 MICROMS IN DIAMETER, SAID COMPOSITION CONTAINING AN ALKALI METAL DERIVATIVE OF AN UNSATURATED HYDROCARBON HAVING A MOLECULAR WEIGHT OF ABOUT 100 TO 2,000 AND AN IODINE NUMBER OF 50 TO 450 IN AN AMOUNT NOT EXCEEDING 15% BY WEIGHT OF SAID COMPOSITION AND EQUAL TO 1 TO 25% BY WEIGHT OF THE ALKALI METAL CONTENT OF SAID COMPOSITION, SAID AMOUNTS OF SAID DERIVATIVE BEING CALCULATED IN TERMS OF ITS PARENT UNSATURATED HYDROCARBON. 